The court-martial for accused Fort Hood shooter Maj. Nidal Hasan was pushed back to June 12 during a pre-trial hearing Thursday.

The trial was to begin March 5 but military judge Col. Gregory Gross ruled it should be delayed three months, at the request of Hasan's defense counsel.

Hasan is charged with 13 counts of pre-meditated murder and 32 counts of attempted, pre-meditated murder. If convicted, he could face the death penalty. The 40-year-old major is accused of carrying out the Nov. 5, 2009, mass shooting at Fort Hood's Soldier Readiness Processing Center that left 13 dead.

As in previous court appearances, Hasan wore an Army combat uniform and a green beanie hat. Armed Fort Hood police escorted him in and out of the courtroom in a wheelchair. He was paralyzed when shot by Fort Hood police on the day of the incident.

Government-appointed lead defense attorney Lt. Kris R. Poppe cited the large amount of material attorneys must sift through and the need for mitigation expert Tim Semmerling to complete a background investigation on Hasan as reasons for the requested delay.

Mitigation experts are employed in death penalty cases to develop psychological profiles and personal histories of defendants.

Although Gross sided with the defense, the judge did not grant the request for a July trial date. He said the defense showed enough evidence to grant the continuance, but chided the mitigation expert for not having completed his investigation.

"I am not convinced that this case has been (Semmerling's) top priority," said Gross.

Semmerling was not present at the hearing.

At the government's expense, the defense hired Semmerling as an expert in April 2010. Since then, he has billed the government for 1,600 hours of work at a cost of more than $250,000, lead prosecutor Lt. Col. Steve Henricks told the court.

Poppe said Semmerling is researching Hasan's family, cultural and religious backgrounds, as well as his medical history.

In addition, Poppe said the defense has received more than 60,000 pages of documents regarding Hasan's case from the government since December. Prior to that, the defense already had amassed 320,000 pages of documents.

"The amount of discovery is mind-boggling," Poppe told the court.

Gross also granted a defense request for a jury selection expert, who will assist in questioning prospective members of the panel of Army officers from Fort Sill, Okla., who will serve as the jury. The military judge denied an additional defense motion for a pre-trial publicity expert.

Contact Philip Jankowski at philipj@kdhnews.com or (254) 501-7553. Follow him on Twitter at KDHcrime.